The invention covered in the present application relates in general to behavior modifying control of pulsating activity in different types of systems.
Pulsating activity systems are disclosed in U.S. Pat. Nos. 5,342,401, 5,447,520, 5,522,863 and 5,797,965 to Spano et al., such patents being issued from applications which are interrelated with the parent application of the present application by virtue of at least two common co-inventors and by sequential copendency beginning with the filing of the earliest of the applications for U.S. Pat. No. 5,342,401 on Aug. 19, 1992 to the filing date of Jul. 8, 1996 for the parent application of the present application, which was a continuation-in-part of the application which matured into the aforementioned U.S. Pat. No. 5,797,965. During pendency of the applications from which the aforementioned U.S. Pat. Nos. 5,342,401, 5,447,520 and 5,522,863 matured, an article authored by the co-inventors in the present application and relevant to the present invention was published May 29, 1995 in xe2x80x9cPhysical Review Lettersxe2x80x9d, Vol. 74, No. 22, on pages 4420-4423. The disclosures in all four of the aforementioned U.S. Patents to Spano et al., as well as that of the latter referred to publication are incorporated herein by reference.
Pulsating activities exhibiting a deterministic phenomenon known as chaos exists in both physical and biological systems. Such a physical system is known to be established for example in a magneto-elastic ribbon anchored at one end and to which a sinusoidally varying magnetic field is applied to induce therein intermittent chaos. Biological systems on the other hand involving living tissue or neural networks within which chaos is induced, are disclosed in the aforementioned U.S. patents to Spano et al. Such disclosures cover utility methods involving activity modification of the system, which is effected through electrical stimuli intervention following measurement recording and monitoring of pulsating activity events plotted on a return map from which various control strategies are determined for computer programmed behavior modification.
It is therefore an important object of the present invention to provide a more readily implemented strategy for sustaining chaos behavior in systems which otherwise exhibit intermittent or transient chaos, such those referred to in the aforementioned U.S. patents to Spano et al. in connection with useful purposes such as medical diagnosis and treatment of cardiac arrhythmia and treatment of epileptic foci in the neuronal network of living brain tissue.
In accordance with the present invention, an anticontrol method for maintenance of chaos behavior in a system exhibiting periodicity, involves infrequent application of time-dependent perturbations of a single parameter of the system which is readily accessible to measurement and recordation as graphical points on a return map providing a dynamic representation of the system being monitored. The concentration of graphical measurement points within a plurality of regions are located and identified on the return map as following paths or routes toward a loss region from which periodicity follows. Transition to periodicity occurs from the loss region when progression from chaos behavior along one route is initiated. A behavior modifying signal is applied to the system upon initiation of the progression toward periodicity to cause diversion from such route. Loss of chaos is thereby prevented without interference with progression along other routes to the loss region in order to reliably sustain chaos.
The success of the foregoing chaos anticontrol method has been demonstrated in a physical type of system having a magnetoelastic ribbon clamped at one end, as referred to in the aforementioned publication xe2x80x9cPhysical Review Lettersxe2x80x9d, volume 74, Number 22, pages 4420-4423.
In accordance with the present invention, the measurement data heretofore obtained from a chaos embodying system to dynamically represent its pulsating activity by plotting on a return map, is utilized to institute intervention for chaos maintenance in either a physical or a biological system. Thus, the concentration of plotted measurement data points within the loss region on the return map is monitored in order to control the timing and magnitude of an intervention signal based on the location of such loss region along a path of progression from chaos to periodicity.